1. Field of The Invention
This invention relates to EMD locomotive engine protective devices and more particularly to overriding the protective devices in an EMD locomotive engine during a computer controlled automatic engine shutdown and restart system.
2. Description of Related Art
It is a generally recognized fact that locomotives spend 40-50% of their time idling, (Assoc. of American Railroad, Report No. R-506). In order to prevent the wasting of thousands of gallons of fuel, many locomotives are now equipped with automatic engine shutdown and restart system. These are computer controlled systems which monitor a variety of parameters such as: reverser position; throttle position; air brake cylinder pressure; engine coolant temperature; ambient air temperature; battery voltage and battery charging amperage. By monitoring these parameters, the computer program can safely shut off the locomotive engine while it is idling and automatically restart the engine in accordance with program parameters. By cutting idle time, the railroad saves as much as $15,000 a year for each equipped locomotive. Also, the system reduces the particulate gaseous and noise emissions generated by idling locomotives as well as cutting down on wear and tear on the locomotive engine. Applicant manufactures and sells an automatic shutdown or restart system called "ZTR SmartStart.TM.". The ZTR SmartStart.TM. system was implemented in connection with locomotives equipped with Caterpillar diesel engines in February of 1991. Because Caterpillar diesel engines utilize unique electronic governor and engine block designs, they lend themselves readily to automatic shutdown and restart.
When applicant attempted to adapt the ZTR SmartStart System to work in connection with Electro-Motive division of General Motors locomotive engines (EMD) applicant discovered that certain protective devices on these engines made automatic shutdown and restarts more difficult on this type of engine.
The first edition (April 1978), sec. 13 and second edition (1984) of the EMD Engine Maintenance Manual discusses these protective devices in detail. The EMD Maintenance Manual is hereby incorporated by reference. To briefly summarize, the protective devices consist of a mechanical crankcase pressure detector and a low water detector. If the device detects a positive crankcase pressure or low coolant level, the appropriate detector senses this condition and initiates engine shutdown. To manually start an EMD engine, on a consistent basis, the engineer may be required to override the crankcase pressure/low water device by manually holding in one or both buttons on the device, for a predetermined amount of time, to prevent them from tripping and initiating a shutdown. Once the engine water pressure, engine oil pressure and crankcase vacuum have stabilized the reset buttons can be released and thereafter operate normally to protect the engine in case of an abnormal engine condition. It is due to the necessity of having to manually override these reset buttons that an automatic shutdown start up system is difficult to implement on an EMD engine.
Another difficulty that arose in implementing an automatic shutdown start up system was replacing the manual movement of the "layshaft". During a manual engine start of the standard EMD engine, the engineer while cranking the engine will push on the governor "layshaft" which moves the injector control arm. After the engine is running by itself the engineer will hold in (if necessary) either one or both of the engine protection buttons (discussed in the previous paragraph) until water has filled the system and the engine oil pressure has stabilized.
Applicant is aware of one prior attempt to create an automatic start up/shutdown system in connection with an EMD engine. This system was created by Harmon Industries in late 1986. The Harmon Industries Automatic Start Up/Shutdown System Manual--EMD Version (dated August 1986) discloses using air pressure to mechanically actuate a rod which depresses the low water protector reset button during auto start. A mechanical approach as disclosed by Harmon Industries is inherently prone to break down. Also, anecdotal evidence indicates that the Harmon EMD system was unreliable. Harmon also used an air pressure driven mechanical arm to push on the injector control rack, thereby simulating an engineer mechanically moving the "layshaft". Again, this mechanical approach is inherently prone to break down.